Update (2:30 p.m.):Heyward-Bey was released from Eden Medical Center Monday morning with a concussion and neck strain, the Raiders said. He is resting at home and is expected to make a full recovery, according to the report.

Heyward-Bey was running across the end zone and trying to catch a pass when he was sandwiched between a pair of Steeler defenders. Pittsburgh safety Ryan Mundy hammered the receiver in the chest while his helmet collided with Heyward-Bey’s facemask.

The third-year receiver lost consciousness on the play, and his eyes remained closed for 10 minutes while trainers attended to his motionless body on the turf. The hit did not draw a flag from the officials.

Heyward-Bey did lift his arm and give a thumbs up as he was carted off the field, drawing a roar from the previously-hushed fans at the Oakland Coliseum.

The hit will likely draw a significant fine from the NFL, but the play was yet another example of increased downfield contact that has gone unchecked by the league’s much-maligned replacement officials. Several coaches and players have complained about increasingly physical play in the secondary, and defensive backs appear to be taking advantage of the lack of whistles.

“I didn’t go in there trying to hit him with my helmet,” said Mundy, who quickly dropped to a knee and prayed for his fallen foe. “Things like that happen so fast. He may have come down to the level of my helmet. I have to see the replay, I don’t know.”

The NFL maintains that the replacement officials are doing credible work and last week warned teams about their on-field behavior toward the referees, citing the old “respect the game” slogan. But the officials continue to struggle to rein in physical play — as evidenced by the repeated on-field skirmishes in Sunday night’s Ravens-Patriots game.